In the field of graphic arts, an image formation system providing ultrahigh contrast (especially a gamma exceeding 10) is required for achieving satisfactory reproduction of a dot image having continuous tone or a line image.
Image formation systems of using hydrazine derivatives have been proposed to obtain a high contrast image while using a stable developing solution as disclosed in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, and 4,211,857. According to these systems, ultrahigh contrast and high sensitivity can be obtained. Further, since addition of a sulfite to a developing solution in a high concentration is permissive, stability of the developing solution against air oxidation can be greatly improved over lith developers. Nevertheless, hydrazine compounds which have been proposed to date turned out to have several disadvantages. That is, while it has been attempted to make the structure of hydrazine compounds non-diffusive for the purpose of minimizing adverse influences which may arise from the hydrazine compounds dissolved in a developing solution. These non-diffusive hydrazine compounds should be used in large quantities for sufficient sensitization and improvement in contrast so that they are apt to cause deterioration of physical properties of the developed light-sensitive layers or to precipitate in a coating composition. Further, when a light-sensitive material containing such a non-diffusive hydrazine compound fails to obtain sufficient high contrast when developed with a fatigued developing solution after use for processing a large volume of photographic materials.
In addition, a high contract system using the conventional hydrazine compound involves use of a developing solution having a relatively high pH, e.g., 12.0 or higher, which entails not only danger or handling but cost for waste liquid treatment due to high BOD or COD. Because a large amount of a pH buffer must be added to a developing solution for maintaining the pH constant, the developing solution is sticky due to the so increased solid content and is hardly wiped away when scattered.
It has therefore been demanded to develop a hydrazine compound which can achieve high contrast image formation while using a developing solution having a lower pH than in the systems using a conventional hydrazine derivative.
On the other hand, light-sensitive materials for dot-to-dot work which are generally handled in a bright room occupy a large proportion in the field of photomechanical processing. In this field, high reproducibility in formation of super-imposed letters even with a fine line width is demanded. To meet the demand, development of a nucleating agent having improved activity has been long awaited. The expectation for a nucleating agent with higher activity is particularly high for use in light-sensitive materials having low sensitivity so as to be handled in a bright room because they hardly undergo the activity of a nucleating agent.